MAX1472_05 Datasheet, PDF (8/9 Pages) Maxim Integrated Products – 300MHz-to-450MHz Low-Power, Crystal-Based ASK Transmitter

300MHz-to-450MHz Low-Power, Crystal-Based
ASK Transmitter
Layout Considerations
A properly designed PC board is an essential part of
any RF/microwave circuit. On the PA output, use con-
trolled-impedance lines and keep them as short as
possible to minimize losses and radiation. At high fre-
quencies, trace lengths that are on the order of λ/10 or
longer can act as antennas.
Keeping the traces short also reduces parasitic induc-
tance. Generally, 1in of PC board trace adds about
20nH of parasitic inductance. The parasitic inductance
can have a dramatic effect on the effective inductance.
For example, a 0.5in trace connecting a 100nH induc-
tor adds an extra 10nH of inductance, or 10%.
To reduce the parasitic inductance, use wider traces
and a solid ground or power plane below the signal
traces. Using a solid ground plane can reduce the par-
asitic inductance from approximately 20nH/in to 7nH/in.
Also, use low-inductance connections to ground on all
GND pins, and place decoupling capacitors close to all
V_DD connections.
Functional Diagram
DATA
ENABLE
AND
GATE
MAX1472
PA
XTAL1
XTAL2
LOCK DETECT
32 x PLL
CRYSTAL-
OSCILLATOR
DRIVER
V_DD
PAOUT
PAGND
GND
Chip Information
TRANSISTOR COUNT: 1430
PROCESS: CMOS
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